Release hook for aircraft and the like



March 19, 1946. L. c. LESLIE 9 I RELEASE HOOK FQR AIRCRAFT AND THE LIKE Filed Aug. 1s, 1944 v I. .68 Q1 Q' INVENTOR. Lqona wdCficmfesleslc I y v INTO/BN5 y Patented Mar. 19, 1946 RELEASE HOOK FOR AIRCRAFT AND THE LIKE I Leonard Charles Leslie, Northmead, Benoni,

Transvaal, Union of South Africa 1 Application August'18, 1944, Serial No. 550,008 In Union of South'Africa March 24, 1944 6 Claims.

This invention relates to release hooks for detaching the launching or towing rope or cable used in launching r towing aircraft such a gliders, sail-planes and the like.

The object of this invention is to provide a hook or holding device for the end of the launching or towing rope embodying mechanism for the normal release of said rope by manual operation of the flyer but which, should the fiyer neglect to effect the release, will function to release the rope automatically when such rope makes 3. dangerous or undesirable angle with the longitudinal axis of the towed craft. A further object is to provide in such mechanism a normally closed hook with one half hinged and locked by a spring held block sliding on the stem of the hook and capable of movement towards its end. The stem of-the hook is connected by a swivel attached to the nose of the aircraft and the sliding of the block thereon is effected in the normal way by the pull of a cord. Otherwise the sliding of the block is effected by its contact with cams fixed in suitable relation to the axis of the swivel holding the end of the stem of the hook, the movement of the hook about the swivel being effected by the towing rope. V

The accompanying drawing illustrates the preferred form of the apparatus in which:

Fig. 1 is the assembly with part broken away.

Figs. 2 and 3 are diagrammatic views.

9 is a metal box attached to and forming the nose ll] of the aircraft, 1 l is the hook having the hinged piece I2 for closing the same. I3 is the stem of the hook H pivoted on a pin it passing through a perforated head [5 screwed onto the end It of the stem I3. I! is a'block having conveniently a polygonally shaped hole [8 sliding on a similarly shaped part IQ of the stem I3. 20 is an eye bolt adapted to rotate in a bearing block 2| which is secured to the box 9.

The block 2| may be fixed directly to the box 9 but as illustrated it is made to swivel on pintles 22 which extend through the lower part of the housing 23 and also the top plate 24 fastened to the housing 9. The extent. of theswingor angular movement of the block 2| is limited as shown by its flange 25 making contact with the edges 26 of the housing as shown in Fig. 2 which form cam surfaces which, when the hook ll moves down towards the position shown by the dotted lines in Fig. 1, make contact with the edges 3! of block I! and move it on stem l3'towards the head l5 of hook H and so allow hook H to open (as shown by the dotted lines Fig. 1).

The hook H hasa portion l2 hinged at 32 and a tongue 33 adapted to be retained in recess 34 in the block I? to keep hook H closed. The portion 12 also provides an opening 35 for the towing rope 2! or terminal rings 3% attached thereto. When, due to the swing of the stem is about I4,

' the cams 3fl move block I! towards it, the recess is a diagrammatic plan view. Fig. 3 is a diagrammatic end View showing how the entire hook II is allowed to swivel on bolt 20 when the pull of the launching rope 21. is at an angle to the vertical.

28 is a boxlike cover having a slot in its curved front face 29, the turned in edges 30 of which 34 moves away from tongue 33 and the hook H opens to release the launching or towing rope 21 which may be carried in the hook H by being attached to one of the rings 36, as shown in Fig. 3.

3'1 is a hook used for towing the aircraft over the ground. 38 is a, cord attached at one end 39 to the block W by which normally the block I! is pulled by the pilot against the pressure of spring 40 away from hook H to allow the latter to open. All is a guide for cord 38. It will be noted that the end of stem l3 is'threaded at 16 and thatby turning head E5 the position of the block ii in relation to cams 30 may be adjusted and consequently the angle may be chosen most suitable for release. It is locked in position by locking nut 42 and if desired by pin 43.

In operation the aircraft having been brought to the launching position and the launching rope 21 connected to hook H the pull is in line with the axis of theaircraft and the hook H remains closed. With continued movement at the necessary speed due to the pull of the launching rope the aircraft rises in the air'. 7 Its flying speed is of course obtained from the pull of the launching rope which may be woundonto a drum in a winch (not shown). Normally the aircraft will fly towards the winch and the launching rope be released bythe pilot before he has got to a vertical position over the winch. Normally, that is without the fitting of this invention. Should he fail to release the rope just before he reaches or when he is overthe winchthe pull of the rope will be downward; the nose of his aircraft will be pulled down and there will be danger of a crash. Generally provision is made to cut the launching rope if it is not released at the proper time but even if this is done the danger still exists of the nose being pulled down by the trailing length of rope being entangled in objects on the ground. This description particularly applies to'the launching of gliders.

In an aircraft fitted with this invention when approaching to a position above the winch the angle made between the launching rope 21 and the longitudinal axis of the aircraft must constantly decrease and approach the vertical. This means that the hook H will approach the position shown by the dotted line in Fig. 1 by swinging down about the pin M. In such a position it'has carried the block 11 over the cams 30 which force the block ll up to compress the spring 40. This results'in the tongue 33 of the hinged portion of hook ll being released. The book then opens automatically to release the launching rope 21 and the aircraft is free to continue its flight without being pulled down by the towing rope 21.

If, for any reason, the aircraft does not fly stem, a tongue on said hinged piece, a recess in bination of a hook, a closing piece for the hook, a

directly towards the winch and the launching rope is in other than an approximately vertical plane below the aircraft the swivel of the bolt in block 2! will allow the hook I I to take up a P p position in relation to the pull of rope 21. For the same reason the block 2| if desired may allow the whole hook mechanism to swivel to a limited extent on pins 22 as already described.

As shown in Fig. 1 a block 44 may limit the upward swing of the hook I I so that the latter cannot swing above the normal longitudinal axis of the aircraft.

Instead of the cam surfaces 30 it will be understood that movement of the block H or other equivalent means for operating hook H may be employed, for instance links (not shown) suitably ivoted between I l and I! may be provided.

The application of the invention to the launching of gliders has been described but it will readily be seen that in other circumstances as when, for instance, the glider is being towed by a powered aircraft the hook may have a full 180 movement and a release effected in an upward pull in addition and in a similar manner to the downward pull described.

This invention provides a releasing hook for the launching rope or if desired for a towing rope for aircraft which can be set automatically to release the rope when its pull in relation to the aircraft assumes a dangerous angle but which at all times can be readily released by the pilot.

Having now particularly described and ascertaine the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. In a device for holding and releasing the rope used for launching or towing aircraft the combination of a hook, a closing piece hinged to the hook, a stem for the hook, a block slidable on said stem, a tongu on said hinged piece, a recess in the block to engage the tongue, a mountin ena ing he end of the stem to allow the hook to swing up and down and sideways, cams in the downward path of the block to engage with the same and a spring for forcing the block on the stem towards the hook.

2. In a device for holding and releasing the rope used for launching or towin aircraft the comlbination of a book, a closing piece hinged to the hook, a stem for the hook, a block slidable on said stem for the hook, a pin through the end of the stem to allow it to swing up and down, an eye bolt carrying the pin, a swivelling piece allowing the eyebolt to rotate therein, a boxlike casing for the stem of the hook from which the latter I projects, cams in the casing and in the path of the swing of the hook and engaging closing and opening means for the hook, a connection for manually opening the hook and a spring to resist such movement.

4. In a device for holding and releasing the rope used for launching or towing aircraft the combination of a hook, a closing piece hinged to the hook, a stem for the hook, a block slidable on said stem, a tongue on said hinged piece, a recess in the block to engage the tongue, a mounting engaging the end of the stem to allow, the hook to swing up and down and sideways, cams in the downward path of the block to'engage with the same, a spring for forcing the block on the stem towards the hook and a screw threaded end of the stem for. alterin th osition of the engagement of the cams acting to open the hook.

5. In an aircraft towing device, the combination of a hook having a ivotally mounted member normally closing the hook, an elongated stem carried by said hook and mounted for pivotal movement on the aircraft, means slida-ble on said stem for maintaining the ivoted hook member in hookclosing position when in alinement with th longitudinal axis of the aircraft, and cam means in the path of angular movement of said slidable means when the stem is swung on its pivot to a predetermined angle with relation to the longitudinal axis of the aircraft thereby to release the pivoted hookmember and permit the same to swing on its pivot into hook-opening position.

6. In an aircraft towing device, the combination of a hook having a pivotally mounted member normally closin the hook, an elongated stem carried by said hook and mounted for pivotal movement vertically and horizontally or" the longitudinal axis of the aircraft, means slidable on said' stem for maintaining the pivoted hook member in hook-closin position when in the horizontal plane of said longitudinal axis of the aircraft, and cam means in the path of angular movement of said slidable means when the stem is swun on its pivot in a vertical lane to a predetermined angle with relation to the longitudinal axis of the aircraft thereby to release the pivoted hook member and permit the same to swing on its pivot into hook-opening position LEONARD cHAR ns plasma. 

